First Recording of the Fungus Fusarium Oxysporum that Causes Root Rot and Seedling Death on Catharanthus Roseas L. in the Governorates of Karbala and Babylon/Iraq

Abstract

This study was conducted with the aim of isolating and diagnosing the fungus that causes root rot and seedling death of Catharanthus roseas L. in some nurseries in the governorates of Karbala and Babil, and to test its pathogenicity in the laboratory and under greenhouse conditions. The results showed that 11 isolates of Fusarium oxysporum were phenotypically diagnosed and outperformed. Isolate FK8 significantly lowered the percentage of germination of red radish seeds on the water agar medium, as the percentage of germination in it was 3.33% and the inhibition rate was 96.66% compared to the comparison treatment in which the percentage of seed germination was 100%. The results of the plastic pots experiment in the greenhouse also showed that the results matched the laboratory experiment, as isolate FK8 was significantly superior in reducing the germination rate, which amounted to 13.33%, and an inhibition rate of 86.67% when treating the seeds of Catharanthus roseas L. plant with the isolated fungi compared to the comparison treatment, in which the percentage of germination reached 100%. . The results of the molecular diagnosis showed that the most pathogenic isolate FK8 belongs to the fungus Fusarium oxysporum and it was deposited in the American Gene Bank under the entry number on025785.